A conventional direction gauge 1, such as shown in FIGS. 4 and 5, indicates a direction by illuminating any one or more of, for example, 16 indication segments 3 arranged in a ring on a display plate 2. The illuminated segment(s) 3 indicate the direction with respect to the automobile.
Reference markings 4, which may be created by any convenient method such as, for example, printing, indicates such things as a north-south direction line in the vertical direction and an east-west indication in the horizontal direction. Segments 3 are arranged in a ring around reference markings 4. Segments 3 may be of any convenient type such as, for example, LEDs, vacuum fluorescent displays or liquid crystal displays (LCD). Preferably, segments 3 are self-luminous so that they can be viewed in a dark environment. If a vehicle on which direction gauge 1 is mounted travels, for example, in the north-northwest direction, a magnetic sensor built into direction gauge 1 causes the segment that points to north-northwest to light up as shown in FIG. 5, thereby verifying the direction in which the vehicle is traveling.
With such a direction gauge, in a bright place, such as in daylight, the direction indication lettering and indication lines, etc. of reference markings 4 on display plate 2 are seen only in reflected light. Thus the heading direction can be seen according to the relative positions of the display position of the reference markings 4 and the display of the illuminated indication segment 3. But in the dark, such as at night, the reference markings 4 on display plate 2 cannot be seen even when an indication segment 3 is illuminated. This makes it difficult to determine which direction-pointing indication segment 3 is lit up. Consequently, a user must endure the inconvenience in the dark that it is impossible to determine the direction. This reduces or even destroys the effectiveness of direction gauge 1 as a direction gauge.
If the above indication segment 3 showing the direction is in the shape of a dot as above or in the shape of a bar as shown in FIG. 6, it is impossible to distinguish the tip end of a lit segment from its rear end, especially in the dark where the reference markings 4 on display plate 2 cannot be seen. This is inconvenient because the direction indicated by the illuminated segment 3 is ambiguous to the viewer. One way to solve this drawback is to make the indication segments 3 in the shape of an arrow as shown in FIG. 7, so that even with the lit-up display of a single arrow-shaped segment 3, one can determine the direction from the orientation between the pointed end of the arrow-shaped segment 3 and its opposite blunt end.
But the wide base of the arrow shape (triangular shape) as shown in FIG. 7, leaves room for only a small number of arrow-shaped segments 3. As shown in FIG. 7, there is room for only four, or at most eight, such arrow-shaped segments 3. This makes it difficult to indicate the precise direction.
One way to pack more said arrow-shaped segments 3 into a given area would be to give each segment 3 a roughly diamond shape as indicated by the dotted lines in FIG. 7. But then it is difficult to distinguish the sharp upper end of a segment 3 from the only slightly less sharp lower end, thus creating the inconvenience that the display definiteness.
With this invention, when it is assumed that, as in FIG. 8, the segments 3 that indicate direction are made in the form of an arrow in the shape of an isosceles triangle and a large number of these arrow-shaped segments are arranged evenly spaced in a ring with the tips of the arrow shapes pointing radially outward, then depending on the number of arrangements of arrow-shaped segments 3, there will occur, at the part near the base of the arrow-shaped segments 3, overlap parts 3A where portions of adjacent arrow-shaped segments 3 overlap each other.